RELATIONSHIP BETWEEN THE REGIONAL ABUNDANCE OF FOREST AND THE COMPOSITION OF FOREST BIRD COMMUNITIES

We surveyed bird populations in 46 forest tracts in Connecticut, USA, to determine how the distribution of birds is related to forest area, isolation from other forests, and vegetation structure. Both the density and species richness of forest-interior birds tend to be lower in smaller forests. Some species show a significant tendency to be absent from small forests, while others are present in small forests but have higher densities in large forests. This pattern is apparently not related to vegetation structure. Sites that are more isolated from other forests also tend to have fewer forest-interior birds. Forest area is the best predictor of the density and species richness of forest-interior birds for small forests, while isolation is the best predictor for large forests. Our results indicate that maintenance of a diversity of forest-interior birds will require preservation of large areas of forest.